The singers have recorded a track together for Williams' upcoming big band album, a follow-up to his hit 2001 cover record Swing When You're Winning, and Buble confirmed the news during an interview last month (Mar13).

However, Williams was hoping to keep the collaboration a secret before Buble bragged about the project.

He tells the Irish Independent, "Me and Michael was supposed to be a secret for the time being, but since he let the cat out of the bag before me, I'm not in any trouble for once."

The former Take That star goes on to insist he enjoyed working with the Canadian crooner, adding, "I hope we can do it again."